Tips for buying Cath Lab

Devices in the cardiac catheterization field are concerned
with the study and treatment of the heart chambers, coronary arteries, and
other proximal vasculature. Categories in this field may include: Cath Labs, Radiographic Fluoroscopic
units, Digital Vascular Imaging Systems, Angiography Units, Cardiac
Catheterization Equipment and Cardiac Cath Lab Imaging Systems

The preferences and
recommendations regarding angiography are for systems intended mainly for
peripheral and abdominal vasculature cases.

All three types of systems -
cardiac catheterization equipment, general angiography units, and
multipurpose systems - have different requirements regarding the C-arm
assembly, image-acquisition detector, image processor, and patient-table
characteristics.

The requirements of general
angiography systems include: a larger field of view, expended tabletop
movement, a lower frame rate, and C-arm gantry angulation range that is
less than that of dedicated cardiac catheterization equipment.

In some hospitals, the demand
for any one procedural category may not justify a dedicated Cardiac Cath
Lab Imaging System. The multipurpose special procedure systems are
designed to meet such needs. However, both cardiologists and radiologists
should be concerned with detector size.

Rotational angiography
capabilities, which are offered by some Cath Lab systems, allow users to
select start and end points for arm rotation. These systems can be used in
bolus chasing and certain cardiac imaging procedures. Although rotational
angiography is slower than biplane systems, it is useful in studies
traditionally performed with biplane systems.

Facilities that are
considering the purchase of a Cath Lab capable of rotational angiography,
should determine how it applies to the types of procedures performed in
the facility and the rotational speed offered by the Digital Vascular
Imaging System.

One of the most important
factors to consider before purchasing an angiography unit is detector
size. For imaging peripheral vessels, larger sizes may be necessary, while
smaller sizes are suitable for more detailed images of cardiac anatomy.

When selecting an x-ray
generator, facilities must also consider the needs of the department in
mind. The following Digital Vascular Imaging System generators are
currently available and commonly used for vascular imaging: three-phase,
12-pulse, high frequency, and constant-potential generators.

While constant potential
generators have the lowest amount of ripple but can be larger and more
expensive, high frequency generators are smaller and easier to install in
space-constrained areas, with an amount of waveform ripple that is not
clinically significant.

Some additional critical
factors when choosing a Cath Lab are the heat dissipation rate and heat
capacity of the x-ray tube anode. Only 0.2% of the electrical energy
delivered to any given tube is converted to x-rays; the rest is converted
to heat, which will harm the anode if not quickly dissipated.

The following may help
dissipating the heat: rotating and larger diameter anodes, circulated
liquid cooling systems, and ceramic tube envelopes, also crucial when
considering a Cath Lab purchase..

For some advanced
interventional procedures that require longer imaging times, the high heat
capacity and faster heat dissipation tubes are especially important in a
Cath Lab.

Cath Lab anode heat capacity
should be at least 1,000,000 HU.

Facilities should also
consider the Angiography Unit's focal spot size and target angle of the
anode. Anodes with a smaller focal spot provide better quality images but
do not dissipate heat as well as larger ones, which are ideal for
investigating ischemic heart disease. Cath Lab magnification angiography
requires a focal spot size of 0.3 mm or less.

Cath Lab Manufacturers often
offer multi focus tubes with two or three focal spot sizes, to accommodate
this wide range of imaging techniques and procedures.

The focal spot size and the
heat dissipation characteristics of the tube are both determined by the
target angle, another important feature to consider when purchasing a Cath
Lab.

Pulsed fluoroscopy can be
carried out by some of the Cath Lab systems. In this technique an x-ray
output of 32 pulses per second is possible.

The monitor holds the image
acquired during each pulse until it is updated by another pulse; a
continuous image is seen as a result, although the pulsed-mode display may
become jittery a very fast motion is observed.

Exposure rates can be
significantly reduced by pulsed fluoroscopy by as much as 70% without a
significant loss of image information; some Cath Lab systems can perform
multiple-rate pulsed fluoroscopy with two or more rates ranging from 7.5
to 30 fps.

The last-image holding
feature, which retains the fluoroscopic image on the screen even after the
x-rays are turned off, is offered by some Cardiac Catheterization
Equipment systems. This feature enables the radiologist to examine the
area in question with decreased x-ray exposure to the patient.

DSA is the most common
application in Cahth Labs; a mask image is digitally stored before
injection of the contrast medium and then subtracted from the image
acquired after injection.

Another common application is
the road mapping, which allows Cath Lab users to retain a
contrast-enhanced image on the monitor for use as a guide during certain
procedures. Using this feature can facilitate the placement of devices
such as stents and balloons and the navigation of guide wires and
catheters through severe stenoses, as well as reduce the total contrast
medium dose.

Cath Lab Systems offering
three-dimensional angiography should be considered by facilities planning
to purchase new R/F angiographic systems.

Multiple views can be
recorded from a single injection of contrast medium by using rotational
angiography, which is an acquisition mode designed to allow this
capability in Cath Labs.